national ttransportation saaffeetty committee

KNKT.08.10.24.04

PT. Garuda IndonesiaPK – GZI

Boeing Company 737-400Ngurah Rai Airport, Denpasar, Bali

Republic of Indonesia

28 October 2008

Aircraft Accident Investigation Report

NNAATTIIOONNAALL TTRRAANNSSPPOORRTTAATTIIOONN SSAAFFEETTYY CCOOMMMMIITTTTEEEE

NATIONAL TRANSPORTATION SAFETY COMMITTEE MINISTRY OF TRANSPORTATION REPUBLIC OF INDONESIA 2010

FINAL

This Report was produced by the National Transportation Safety Committee (NTSC), Karya Building 7th Floor Ministry of Transportation, Jalan Medan Merdeka Barat No. 8 JKT 10110, Indonesia.

The report is based upon the investigation carried out by the NTSC in accordance with Annex 13 to the Convention on International Civil Aviation, Aviation Act (UU No.1/2009), and Government Regulation (PP No. 3/2001).

Readers are advised that the NTSC investigates for the sole purpose of enhancing aviation safety. Consequently, NTSC reports are confined to matters of safety significance and may be misleading if used for any other purpose.

As NTSC believes that safety information is of greatest value if it is passed on for the use of others, readers are encouraged to copy or reprint for further distribution, acknowledging NTSC as the source.

When the NTSC makes recommendations as a result of its investigations or research, safety is its primary consideration.

However, the NTSC fully recognizes that the implementation of recommendations arising from its investigations will in some cases incur a cost to the industry.

Readers should note that the information in NTSC reports and recommendations is provided to promote aviation safety. In no case is it intended to imply blame or liability.

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TABLE OF CONTENT

TABLE OF CONTENT ........................................................................................................ I

TABLE OF FIGURES ....................................................................................................... III

TABLE OF APPENDIXES ............................................................................................... IV

GLOSSARY OF ABBREVIATIONS ............................................................................... V

SYNOPSIS ............................................................................................................................ 1

1 FACTUAL DATA ....................................................................................................... 2 1.1 HISTORY OF THE FLIGHT .................................................................................... 2

1.2 INJURIES TO PERSONS ........................................................................................ 2

1.3 DAMAGE TO AIRCRAFT ...................................................................................... 2

1.4 OTHER DAMAGE ................................................................................................ 3

1.5 PERSONNEL INFORMATION................................................................................. 3

1.6 AIRCRAFT INFORMATION ................................................................................... 3

1.6.1 General ................................................................................................. 3

1.6.2 Landing gear data ................................................................................. 4

1.6.3 Landing gear data ................................................................................. 4

1.7 METEOROLOGICAL INFORMATION ...................................................................... 4

1.8 AIDS TO NAVIGATION ........................................................................................ 5

1.9 COMMUNICATIONS ............................................................................................. 5

1.10 AERODROME INFORMATION ............................................................................... 5

1.11 FLIGHT RECORDERS ........................................................................................... 5

1.12 WRECKAGE AND IMPACT INFORMATION ............................................................ 5

1.13 MEDICAL AND PATHOLOGICAL INFORMATION ................................................... 6

1.14 FIRE ................................................................................................................... 6

1.15 SURVIVAL ASPECTS ........................................................................................... 6

1.16 TESTS AND RESEARCH ....................................................................................... 6

1.17 ORGANIZATIONAL AND MANAGEMENT INFORMATION ...................................... 6

1.18 ADDITIONAL INFORMATION ............................................................................... 7

1.19 USEFUL OR EFFECTIVE INVESTIGATION TECHNIQUES ........................................ 8

2 ANALYSIS .................................................................................................................. 9 2.1 DETACHMENT OF WHEEL NUMBER-ONE ............................................................. 9

2.2 QUALITY OF THE OVERHAUL (OVERHAUL PROCESS) ......................................... 9

3 CONCLUSIONS ....................................................................................................... 10

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3.1 FINDINGS .......................................................................................................... 10

3.2 CAUSES ............................................................................................................ 10

4 SAFETY ACTIONS .................................................................................................. 11 4.1 PT. GARUDA INDONESIA .................................................................................. 11

4.2 NATIONAL TRANSPORTATION SAFETY COMMITTEE ......................................... 11

4.3 BOEING COMPANY ........................................................................................... 12

5 SAFETY RECOMMENDATIONS ......................................................................... 13

6 APPENDIX ................................................................................................................ 17 6.1 APPENDIX A: LABORATORY OF METALLURGICAL AND MATERIAL

ENGINEERING OF THE INSTITUTE OF TECHNOLOGY, BANDUNG (ITB) REPORT. 17

6.2 APPENDIX B: MATERIAL & PROCESS TECHNOLOGY WORKSHOP BOEING REPORT (FRACTURE ANALYSIS REPORT) ......................................................... 20

6.3 APPENDIX C: AIRCRAFT MAINTENANCE MANUAL B737-300/400/500 ATA CHAPTER 32-41-41 PAGE 403 DATED 25 SEPTEMBER 2009 .............................. 26

iii

TABLE OF FIGURES

Figure 1: The number-one wheel and axle. ........................................................................... 3

Figure 2: The fractured number-one axle showing that the failure occurred near the brake attachment flange .................................................................................................... 6

Figure 3: View of the fracture surface. The fatigue crack initiated from the 5 o’clock attachment hole ....................................................................................................... 7

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TABLE OF APPENDIXES

Appendix A: Laboratory of Metallurgical and Material Engineering of the Institute of Technology, Bandung (ITB) Report. ............................................................... 17

Appendix B: Material & Process Technology Workshop Boeing Report (Fracture Analysis Report) ............................................................................................................. 20

Appendix C: Aircraft Maintenance Manual B737-300/400/500 ATA Chapter 32-41-41 Page 403 dated 25 September 2009................................................................. 26

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GLOSSARY OF ABBREVIATIONS

AD Airworthiness Directive AFM Airplane Flight Manual AGL Above Ground Level ALAR Approach-and-landing Accident Reduction AMSL Above Mean Sea Level AOC Air Operator Certificate ATC Air Traffic Control ATPL Air Transport Pilot License ATS Air Traffic Service ATSB Australian Transport Safety Bureau Avsec Aviation Security BMG Badan Meterologi dan Geofisika BOM Basic Operation Manual °C Degrees Celsius CAMP Continuous Airworthiness Maintenance Program CASO Civil Aviation Safety Officer CASR Civil Aviation Safety Regulation CPL Commercial Pilot License COM Company Operation Manual CRM Cockpit Recourses Management CSN Cycles Since New CVR Cockpit Voice Recorder DFDAU Digital Flight Data Acquisition Unit DGCA Directorate General of Civil Aviation DME Distance Measuring Equipment EEPROM Electrically Erasable Programmable Read Only Memory EFIS Electronic Flight Instrument System EGT Exhaust Gas Temperature EIS Engine Indicating System FL Flight Level F/O First officer or Co-pilot FDR Flight Data Recorder FOQA Flight Operation Quality Assurance GPWS Ground Proximity Warning System hPa Hectopascals ICAO International Civil Aviation Organization

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IFR Instrument Flight Rules IIC Investigator in Charge ILS Instrument Landing System Kg Kilogram(s) Km Kilometer(s) Kt Knots (NM/hour) Mm Millimeter(s) MTOW Maximum Take-off Weight NM Nautical mile(s) KNKT / NTSC

Komite Nasional Keselamatan Transportasi / National Transportation Safety Committee

PIC Pilot in Command QFE Height above aerodrome elevation (or runway threshold

elevation) based on local station pressure QNH Altitude above mean sea level based on local station

pressure RESA Runway End Safety Area RPM Revolution Per Minute SCT Scattered S/N Serial Number SSCVR Solid State Cockpit Voice Recorder SSFDR Solid State Flight Data Recorder TS/RA Thunderstorm and rain TAF Terminal Aerodrome Forecast TSN Time Since New TT/TD Ambient Temperature/Dew Point TTIS Total Time in Service UTC Coordinated Universal Time VFR Visual Flight Rules VMC Visual Meteorological Conditions

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SYNOPSIS

On 28 October 2008, a Boeing 737-400 aircraft, registered PK-GZI, registered PK-GZI, was being operated on a scheduled passenger service from Adisucipto Airport, Yogyakarta to Ngurah Rai Airport, Denpasar. There were 139 persons on board; two pilots, five flight attendants, and 132 passengers.

After landing, while the aircraft was being taxied to the apron, the number-one main wheel axle failed.

The left main landing gear had been overhauled by a United States Federal Aviation Administration approved workshop in the USA. After the overhaul on 28 August 2008, the landing gear was installed on PK-GZI on 24 October 2008. The failure occurred on 28 October 2008. At the time of the failure, the landing gear had completed 15,345 cycles since new, and 7 cycles since overhaul.

The investigation found that an undetected fatigue crack in the number-one main landing gear axle originated from a corroded hole in the brake assembly attachment flange. The fatigue crack propagated toward the flange and the axle wall, reaching about 8 cm long until a fast final fracture occurred. The accident occurred on the seventh landing after the installation of the overhauled main landing gear.

Laboratory examinations on the failed axle were conducted in Indonesia and the USA. Two areas of evidence supported that the crack was present before the inner cylinder was last overhauled.

On 5 August 2008, the operator’s maintenance organization issued engineering orders that required increased inspection schedules for main landing gear axles, because the axle had failed at a time significantly short of the manufacturers specified component life.

On 6 August 2008, the National Transportation Safety Committee issued recommendations to the Directorate General of Civil Aviation, the US Federal Aviation Administration, the Boeing Company, and the European Aviation Safety Agency, with respect to reviewing the overhaul and inspection requirements for Boeing 737 main landing gear axles.

On 20 July 2009, the US National Transportation Safety Board (NTSB) informed the NTSC that “Boeing plans to revise the AMM [Aircraft Maintenance Manual] to add and highlight the importance of visually inspecting the brake flange location part for corrosion and/or damaged Sermetal finish during normal maintenance activities. In addition, Summit Aerospace [component overhaul facility] has taken several safety enhancement actions by adding a fluorescent penetrant inspection in addition to the existing magnetic partial inspection, and revised the relevant magnetic partial inspection techniques to enhance the inspection.”

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1 FACTUAL DATA

1.1 HISTORY OF THE FLIGHT

On 28 October 2008, a Boeing Company 737-400 aircraft, registered PK-GZI, was being operated on a scheduled passenger service from Adisucipto Airport, Yogyakarta to Ngurah Rai Airport, Denpasar. There were 139 persons on board; two pilots, five flight attendants, and 132 passengers.

The aircraft touched down on Denpasar runway 09 at 1412 UTC1. While the aircraft was being taxied to the apron, the number-one2 main wheel axle failed.

None of the aircraft’s occupants were injured.

1.2 INJURIES TO PERSONS

Table 1: Injuries to persons

1.3 DAMAGE TO AIRCRAFT

The number-one main landing gear axle was broken and detached from its landing gear strut.

1 The 24-hour clock used in this report to describe the time of day as specific events occurred, is in

Coordinated Universal Time (UTC). Local time, Western Indonesian Standard Time (WIB) is UTC+ 7 hours.

2 Main landing gear wheels are numbered one to four, with wheel number one the left outboard, and wheel number four the right outboard.

Injuries Flight crew Passengers Total in Aircraft Others

Fatal - - - -

Serious - - - -

Minor - - - Not applicable

Nil Injuries 7 132 139 Not applicable

TOTAL 7 132 139 -

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Figure 1: The number-one wheel and axle.

1.4 OTHER DAMAGE

No other damage was reported.

1.5 PERSONNEL INFORMATION

The pilots held valid licenses and ratings for the operation of the aircraft. This section covering flight crew is not relevant to this serious incident.

1.6 AIRCRAFT INFORMATION

1.6.1 General

Registration Mark : PK-GZI

Manufacturer : Boeing Company

Country of Manufacturer : United States of America

Type/ Model : Boeing 737-400

Serial Number : 29204

Date of manufacture : 1998

Certificate of Airworthiness

Valid to : 20 July 2009

Time Since New : 31,456 hours

Cycles Since New : 16,186 cycles

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1.6.2 Landing gear data

Main landing gear number one Part number : 65-46116

Serial number : MC 06099P3051

Date installed : 24 October 2008

Time Since New : 30,243 hours

Cycles Since New

Cycles Since Inspection

:

:

15,345 cycles

7 cycles

Overhaul limit calendar

Overhaul limit cycles

:

:

10 years

21,000 cycles

The aircraft’s first owner was Sailplane Leasing Ltd. It was operated by Aeroflot with Certificate of Airworthiness Number A16WE E2GL.

The next operators were: • Aeroflot (Reg. VP-BAL) from 17 July 1998 to December 2003.

During that time the aircraft was flown from 7 hours 57 minutes total time in service, to 17,640 hours and 49 minutes, and from 9 cycles to 6,494 cycles.

• Garuda Indonesia (Reg. PK-GZI) commenced operating the aircraft on 22 January 2004 until the date of the accident on 8 November 2008. During that time the aircraft was flown from 17,640 hours and 49 minutes total time in service, to 31,456 hours, and 6,494 cycles to 16,186 cycles.

1.6.3 Landing gear data

The left main landing gear had been overhauled by a United States of America (USA) Federal Aviation Administration (FAA) approved workshop in the USA. After the overhaul on 28 August 2008, the landing gear was installed on PK-GZI on 24 October 2008. The failure occurred on 28 October 2008. At the time of the failure, the landing gear had completed 15,345 cycles since new, and 7 cycles since overhaul.

At the time the aircraft was dispatched for the flight it was certified as being airworthy.

1.7 METEOROLOGICAL INFORMATION

Not relevant to this accident.

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1.8 AIDS TO NAVIGATION


1.9 COMMUNICATIONS

Communication between Air Traffic Services and the crew was normal.

1.10 AERODROME INFORMATION


1.11 FLIGHT RECORDERS

The aircraft was equipped with a Solid State Digital Flight Data Recorder (SSFDR) and a Solid State Cockpit Voice Recorder (SSCVR) with a 30 minutes recording time.

The flight recorders were quarantined by the National Transportation Safety Committee investigators. The Flight Data Recorder was downloaded for the investigation, and the data revealed the G forces and landing speed of the seven flights on the day of the accident as follows:

Sector Route G Force Speed

1 Jakarta – Balikpapan 1.3 134 2 Balikpapan – Jakarta 1.3 120 3 Jakarta – Denpasar 1.4 140 4 Denpasar – Surabaya 1.4 132 5 Surabaya – Denpasar 1.3 140 6 Denpasar – Yogyakarta 1.4 127 7 Yogyakarta – Denpasar 1.1 137

The G forces and landing speeds were normal.

1.12 WRECKAGE AND IMPACT INFORMATION

The number-one main landing gear axle fractured.

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Figure 2: The fractured number-one axle showing that the failure occurred

near the brake attachment flange

1.13 MEDICAL AND PATHOLOGICAL INFORMATION

No medical or pathological investigations were conducted as a result of this accident, nor were they required.

1.14 FIRE

There was no pre- or post-accident fire.

1.15 SURVIVAL ASPECTS

None of the occupants were injured, and they vacated the aircraft unaided via airstairs.

1.16 TESTS AND RESEARCH

Not relevant to this accident investigation.

1.17 ORGANIZATIONAL AND MANAGEMENT INFORMATION

Operator: PT. Garuda Indonesia

Management Building 3rd Floor

Garuda Maintenance Facility

Soekarno-Hatta Airport

Jakarta 19130

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1.18 ADDITIONAL INFORMATION

A metallurgical laboratory examination was performed on the broken axle at the laboratory of metallurgical engineering of the Institute of Technology, Bandung (ITB). The ITB laboratory report is at Part 6, Appendix A.

The crack on the axle originated from one of the brake assembly attachment holes at the axle flange.

The crack propagated about 8 cm until a fast final failure occurred.

Figure 3: View of the fracture surface. The fatigue crack initiated from the

5 o’clock attachment hole

Portions of the crack were present at least 43 cycles before the inner cylinder was last overhauled. The crack was present about 50 cycles before the failure.

Laboratory examinations were also performed by National Transportation Safety Board (NTSB), and the Boeing Company Material and Process Technology Workshop (M&PT). The ITB and M&PT reports concluded similar failure mechanisms.

Furthermore, the M&PT found that there were two areas of evidence that supported that portions of the crack were present before the inner cylinder was last overhauled. One item of evidence was the presence of discolouration on the fracture surface due to heat tinting during overhaul activities. The other evidence was the presence of Sermetal deposits on the crack, which occurred during the overhaul process. The Boeing Company M&PT report is at Part 6, Appendix B.

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Boeing Company Overhaul Manual

The Boeing Company Overhaul Manual (32-11-11 page 301) states:

Examine the brake attachment flange on inner cylinder (62) for signs of cracks. If there are cracks, they will start from the brake mounting holes and could go inwards (toward axle) or outward (toward outer edge of brake flange). No more than four holes can have cracks that go outward. Refer to SB 32-1081 for more data.

1.19 USEFUL OR EFFECTIVE INVESTIGATION TECHNIQUES

The investigation was conducted in accordance with NTSC approved policies and procedures, and in accordance with the standards and recommended practices of Annex 13 to the Chicago Convention.

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2 ANALYSIS

2.1 DETACHMENT OF WHEEL NUMBER-ONE

The investigation determined that the progress of the fatigue crack in the main landing gear axle number-one as follows:

• The failure mechanism was a fatigue failure.

• The fatigue crack originated from a corroded hole of the brake attachment flange.

• The fatigue crack propagated about 8 cm from the origin until a fast final fracture occurred.

The corrosion at the attachment hole increased the stress concentration locally.

The investigation determined that main wheel number-one, together with axle number-one separated from the landing gear assembly due to the propagation of a fatigue crack.

The investigation considered that based on these facts, maintenance activities related to axles and brake flanges should include detection and prevention of corrosion.

2.2 QUALITY OF THE OVERHAUL (OVERHAUL PROCESS)

The accident occurred on the seventh landing after the installation of the overhauled main landing gear.

The US National Transportation Safety Board (NTSB) confirmed the Boeing Company Material and Process Technology Workshop (M&PT) report’s findings. The report concluded that the crack was present at the time of overhaul. However, the crack was not detected during the overhaul.

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3 CONCLUSIONS

3.1 FINDINGS

• The aircraft was certified as being airworthy at the time of accident.

• Both pilots held valid licenses and ratings for the operation of the aircraft.

• A fatigue crack in the main landing gear axle originated from one corroded hole in the brake assembly attachment flange.

• The fatigue crack propagated toward the flange and the axle wall, reaching about 8 cm long until a fast final fracture occurred.

• The fatigue crack, which had extensively propagated, was present prior to the overhaul, and was not detected during the overhaul.

• The accident occurred 7 cycles after the installation of the overhauled left main landing gear.

3.2 CAUSES

• An undetected fatigue crack in the number-one main landing gear axle originated from a corroded hole in the brake assembly attachment flange.

• The fatigue crack propagated toward the flange and the axle wall, reaching about 8 cm long until a fast final fracture occurred.

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4 SAFETY ACTIONS

4.1 PT. GARUDA INDONESIA

On 5 August 2008, Garuda Indonesia informed the National Transportation Safety Committee that it had taken the following safety actions.

a) Amended its inspection policies and procedures (Continuous Airworthiness Maintenance Program) with respect to Boeing 737-300/400/500 series aircraft main landing gear assemblies, which requires maintenance inspection to:

b) Conduct one time inspections, in accordance with Garuda Indonesia Engineering Order B3/P32-00-0354R1, on Landing Gear Assemblies on all Garuda Indonesia Boeing 737-300/400/500 series aircraft which have accumulated 15,000 Cycles Since Overhaul as of 23 July 2008, are to be performed before 17 August 2008. The inspections are non destructive using ultrasonic method for the outer surface of the axle root and eddy current method for the flange area (including brake attach flange, flange holes and adjacent axle surfaces).

c) In accordance with Garuda Indonesia Engineering Order B3/S32-00-0355 perform non destructive inspection on Main Landing Gear Brake Attachment Flange on Inner Cylinder Assembly using Eddy Current method and outer surface of axle root using Ultrasonic method during every “C” Check.

d) If during inspection, crack or severe damage indicates in one or more brake mounting holes, or any other parts of the assembly, the Landing Gear Inner Cylinder Assembly should be replaced with a serviceable one.

4.2 NATIONAL TRANSPORTATION SAFETY COMMITTEE

On 24 November 2009 the NTSC issued the following recommendations with the issue of Preliminary Report KNKT.08.10.24.04.

As result of this investigation to date, the National Transportation Safety Committee (NTSC) proposes several recommendations, to overcome identified safety deficiencies.

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The investigation into the 28 October 2008 main landing gear axle failure of Boeing 737-400 aircraft, registered PK-GZI, has identified that the fracture also originated in a brake attachment flange of the main landing gear axle. The component had completed eight flight cycles since overhaul at a US Federal Aviation Administration (FAA) approved overhaul workshop. The axle assembly had completed 15,352 flight cycles since new.

The investigation to date indicates that the crack commenced more than 50 flight cycles before the failure. Therefore, the NTSC reiterates the safety action taken by Garuda Indonesia on 5 August 2008 and the recommendations made to the Boeing Company and the US FAA via the US National Transportation Safety Board (NTSB), and the European Aviation Safety Agency (EASA), on 6 August 2008, to overcome identified safety deficiencies.

4.3 BOEING COMPANY

On 11 February 2010, the National Transportation Safety Board advised the National Transportation Safety Committee that:

“Boeing has revised the Airplane maintenance Manual (AMM) to provide for enhanced visual inspection of the coating on the brake attachment flange at each brake change. The revised AMM inspection is included for your information.”

The Boeing AMM revision is at Appendix C.

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5 SAFETY RECOMMENDATIONS

On 6 August 2008, the National Transportation Safety Committee (NTSC) issued the following safety recommendations as a result of findings in the investigation of a failed main landing gear axle on a Boeing 737 aircraft, registered PK-GZN, which occurred on 23 July 2008. The recommendations are reiterated as follows.

Directorate General of Civil Aviation

Recommendation KNKT/08.16.07.03 A

The National Transportation Safety Committee recommends that the Directorate General of Civil Aviation of the Republic of Indonesia require that Indonesian operators of Boeing 737-200/300/400/500 series aircraft affected by The Boeing Company Overhaul Manual (32-11-11 page 301) instructions to:

a) Conduct one-time non destructive inspections on Landing Gear Assemblies on all Boeing 737-300/400/500 series aircraft which have accumulated 15,000 Cycles Since Overhaul. Specifically, the inspections should be conducted on the outer surface of the axle root and the flange area (including brake attach flange, flange holes and adjacent axle surfaces).

b) Conduct Eddy Current inspections of the brake attachment flange on inner cylinder and Ultrasonic inspections of the outer surface of axle root of Boeing 737-200/300/400/500 series aircraft at each ‘C’ check inspection;

c) Replace Inner Cylinder/Sliding Member assemblies whenever a crack is found in one or more brake mounting holes or any other part of the assembly.

United States Federal Aviation Administration

Recommendation KNKT/08.16.07.03 B

The National Transportation Safety Committee of the Republic of Indonesia recommends that the US Federal Aviation Administration require the Boeing Company to amend the Boeing 737 Overhaul Manual (32-11-11 Page 301) to require operators of Boeing 737-200/300/400/500 series aircraft affected by Overhaul Manual (32-11-11 page 301) instructions to:

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United States Federal Aviation Administration

Recommendation KNKT/ 08.16.07.03 C

The National Transportation Safety Committee of the Republic of Indonesia recommends that the US Federal Aviation Administration require operators of Boeing 737-200/300/400/500 series aircraft affected by Overhaul Manual (32-11-11 page 301) instructions to:

a) Conduct one time non destructive inspections on Landing Gear Assemblies on all Boeing 737-300/400/500 series aircraft which have accumulated 15,000 Cycles Since Overhaul. Specifically, the should be conducted on the outer surface of the axle root and the flange area (including brake attach flange, flange holes and adjacent axle surfaces).



15

Boeing Company

Recommendation KNKT/ 08.16.07.03 D

The National Transportation Safety Committee of the Republic of Indonesia recommends that the Boeing Company amend the Boeing 737 Overhaul Manual (32-11-11 Page 301) to require operators of Boeing 737-200/300/400/500 series aircraft affected by The Boeing Company Overhaul Manual (32-11-11 page 301) instructions to:




European Aviation Safety Agency

Recommendation KNKT/ 08.16.07.03 E

The National Transportation Safety Committee of the Republic of Indonesia recommends that the European Aviation Safety Agency require operators of Boeing 737-200/300/400/500 series aircraft affected by The Boeing Company Overhaul Manual (32-11-11 page 301) instructions to:


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17

6 APPENDIX

6.1 APPENDIX A: LABORATORY OF METALLURGICAL AND MATERIAL ENGINEERING OF THE INSTITUTE OF TECHNOLOGY, BANDUNG (ITB) REPORT.

DRAFT REPORT METALLURGICAL OBSERVATION

ON THE FAILED MAIN LANDING GEAR AXLE OF GARUDA INDONESIA BOEING 737-400 PK GZI

AT NGURAH RAI AIRPORT, BALI ON 28 OCT 2008

1. REFERENCE

This observation is performed in response to NTSC (KNKT) Department of Transportation RI, letter no. KNKT/175/X/KTJ/08 dated 30 October 2008.

2. OBSERVATION

Figure 1: Broken axle. Failure occurred near the brake attachment flange

Figure 2: Fracture surface: final failure. Fatigue crack was initiated from the 5o’clock attachment hole.

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Figure 3: Beach marks started from the hole, propagated inward toward the axle.

Figure 4: The appearance of fracture surface on the matching piece. Beach-marks reached approximately 8 cm from the hole.

Figure 5: Fretting/corrosion pits on the surface of the flange hole

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3. CONCLUSION:

a. The fatigue crack had propagated up-to 8 cm from the origin.

b. The beachmark is certainly of large number of cycles. The failure occurred at 8 flight cycles after the overhaul at SUMMIT Aerospace, USA.

c. Fretting/corrosion pits were observed on the surface of the flange hole.

d. The fatigue crack was initiated from that fretting pits.

4. QUESTION

Questions arise from the investigation are as follows:

a. Why during the overhaul the crack was not detected?”

b. Is the MPI (Magnetic Particle Inspection) effective to detect such a crack?”

Bandung, 8 November 2008

Laboratory of Metallurgy & Materials Engineering

Faculty of Mechanical and Aerospace Engineering ITB

Dr. ir. Arif Basuki

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6.2 APPENDIX B: MATERIAL & PROCESS TECHNOLOGY WORKSHOP BOEING REPORT (FRACTURE ANALYSIS REPORT)

26

6.3 APPENDIX C: AIRCRAFT MAINTENANCE MANUAL B737-300/400/500 ATA CHAPTER 32-41-41 PAGE 403 DATED 25 SEPTEMBER 2009

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